Vesiculated polymer granules

ABSTRACT

Vesiculated granules of cross-linked carboxylated polyester resin prepared by the free radical polymerization of a dispersion of an ethylenically unsaturated monomer, a carboxylated unsaturated polyester resin having an acid value of from 5-50 mg KOH/g and an alkyl acryloyl derivative. Aqueous compositions comprising the granules are used in conjunction with fibrous cellulosic or non-cellulosic materials for the preparation of paper containing the vesiculated polymeric granules dispersed therein. The paper has improved optical opacity.

This is a divisional of application Ser. No. 095,419 filed Sept. 8,1987, now U.S. Pat. No. 4,808,633.

This invention relates to vesiculated polymer granules, aqueouscompositions comprising said granules and to said compositionscomprising said granules and fibrous material of use in papermaking.

Paper is typically made from aqueous suspensions of fibrous cellulosicor non-cellulosic material which may have been delignified and/orbleached, e.g. plant matter, such as trees, cotton, bagasse, andsynthetic polymers, such as rayon. To the aqueous fibrous suspension aregenerally added sizing materials, wet and dry strength additives,defoamers, biocides, dyes, and particularly, retention aids and fillers.The suspension (furnish) is transferred to a forming wire for waterdrainage to concentrate solids, and subsequently dried to the desiredbasis weight.

The development of fibrous systems having a high opacity has always beena concern to paper manufacturers. The degree of opacity of a particularsubstrate is the result of diffuse light-scattering which occurs whenvisible radiation is reflected from particles on the surface of thesubstrate and in the substrate medium itself. It has been customary touse high density inorganic mineral fillers, such as calcium carbonateand certain clays, to enhance the opacity of paper sheets.Unfortunately, the use of such fillers has several disadvantages in themanufacture of paper. Most inorganic mineral fillers possess a lowopacity-to-weight ratio when included in paper. In addition, thegenerally low retention of the inorganic mineral opacifiers in the paperresults in a financial loss by virtue of the by-product waste producedfrom the wire during sheet formation. More importantly, this poor fillerretention may result in contamination of streams, lakes and otherwaterways.

It is customary to incorporate in the dilute paper furnish, just beforeformation on the wire, small amounts of polyelectrolyte retention aidsto give improved retention of the fibrous material, fillers and fines onthe wire during sheet formation. This reduces, somewhat, the loss of thefiller to the by-product waste.

It has been suggested that microencapsulated polymers can beincorporated in a paper sheet to enhance opacity. The substantiallyspherical polymers can be added in the dilute paper furnish beforeformation on the wire as substitutes for inorganic mineral fillers.These microcapsular opacifiers can also be incorporated in coatings forfibrous or non-fibrous substrates. For example, Canadian Patent No.856,861 describes polymer granules with a vesiculated structure that canbe utilized in a coating composition and polymer films to impart anopacity which is greater than non-vesiculated granules of the samecomposition.

It is an object of the present invention to provide a means forincreasing the retention of pigmented and/or non-pigmented vesiculatedgranules in a paper sheet.

It is further object of the present invention to provide a reduction inthe amount of opacifier which is lost during the formation of paper onthe forming wire.

Accordingly, the invention provides vesiculated granules of cross-linkedcarboxylated polyester resin of the type prepared by the free radicalpolymerization of a dispersion comprising (a) an ethylenicallyunsaturated monomer; (b) a carboxylated unsaturated polyester resinhaving an acid value of from 5-50 mg KOH/g; (c) water; and (d) a base;characterised in that said dispersion further comprises a polymerizablealkyl acryloyl derivative of the formula: ##STR1## where R₁, R₂ and R₃are selected from H and CH₃ ; E is NH or O; R₄ is C₁₋₆ alkyl substitutedwith Z; wherein Z is NR₅ R₆ ; wherein R₅ is C₁₋₄ alkyl and R₆ is H; orR₅ and R₆ are independently C₁₋₃ alkyl; and quaternary C₁₋₃ alkyl saltsthereof.

Preferably, the alkyl acryloyl derivative has the formula: ##STR2##wherein R₁, R₂, R₃ and E are as hereinbefore defined

and n is selected from 1-3.

The vesiculated beads provided herein have a highly cross-linkedpolymeric body preferably constituted by a carboxyl-functionalunsaturated polyester resin cross-linked with an ethylenicallyunsaturated monomer and an alkyl acryloyl derivative copolymerizedtherewith.

We have found in accordance with the present invention that the chemicalincorporation of an alkyl acryloyl derivative electrolyte within apigmented or non-pigmented vesiculated granule to constitute apolyelectrolyte retention aid provides enhanced retention of saidgranule, filler and fines within a fibrous cellulosic or non-fibrouscellulosic paper sheet. Surprisingly, it has been found that when thesepigmented and/or non-pigmented vesiculated granules are added to anaqueous paper pulp furnish before being formed into a paper sheet on theforming wire, the resulting paper sheet achieves an enhanced opacity.

Thus, in a further feature the invention provides an aqueous compositioncomprising vesiculated granules according to the invention ashereinbefore defined and a fibrous cellulosic or non-fibrous cellulosicmaterial in the form of a paper pulp.

In a further feature of the invention, the vesicles contain particulatesolids up to 65% by weight, expressed as a solid on the solid portion ofthe granule. The particulate solids may be dispersed in a liquid inwhich the polymer is insoluble or may be associated with essentiallygaseous components alone. For example, the particulate solids used inthe granules may be any suitable organic or inorganic filler. Suchfillers include those finely divided materials which have beenconveniently employed for the purpose of enhancing optical properties,such as opacity, in a paper sheet. Suitable fillers include, forexample, TiO₂, CaCO₃, Al₂ O₃.3H₂ O, barytes (BaSO₄), clay, CaSO₄,CaSiO₃, talc, and the like. Preferred inorganic fillers for the purposeof the present invention are TiO₂, CaCO₃, Al₂ O₃.3H₂ O, BaSO₄, and clay,with titanium dioxide being particularly preferred.

Any desired filler particle size may be used, as long as it is suitablefor incorporation into he vesicular structure. Thus, for example,titanium dioxide having a mean particle size between 0.1 and 0.35microns is highly suitable for the purposes of this invention.

The technique of preparing porous granules from carboxylated,unsaturated polyester resin by emulsifying water into the polyesterresin in the presence of a base and then polymerizing the resin has beenknown for some time. The background to the subject is well covered inthe literature, for example, in articles by Kershaw (Australian OCCAProceedings and News, 8 No. 8, 4 (1971)), and Treier (TAPPI, 55 No. 5,(1972)). Numerous patents relating to these granules have also beenissued, which include U.S. Pat. Nos. 3,822,224; 3,879,314; 3,891,577;3,933,579; 4,089,819; 4,321,332; and particularly, Canadian Patent No.1,139,048. Although it is not intended to limit the present invention toany particular process of manufacture or choice of carboxylated,unsaturated polyester resins of which the vesiculated beads arecomprised, the process of preparation of vesiculated polyester resingranules as outlined in Canadian Patent No. 1,139,048 is preferred.However, in the preparation of prior art vesiculated granules it isknown that a thickening agent is required to stabilize the granulesafter formation by the "double emulsion" process. In the absence of thethickener, or constant agitation, the granules will settle into ahard-packed layer at the bottom of the container. This tendency tosettle or aggregate is undesirable in that "grit" particles may form,and the settled layer is difficult to resuspend. A further disadvantageis the requirement of additional amine to the system to activate thethickener, which contributes to an undesirable odour.

Surprisingly, we have now found that it is possible to preparedimensionally stable granules by a double emulsion process from whichall the suspending thickener and associated amine can be eliminated.

Accordingly, in a further aspect the invention provides an aqueouscomposition comprising vesiculated granules as hereinbefore defined.

Carboxylated unsaturated polyesters which will cross-link by reactionwith ethylenically unsaturated monomers are well known. Suitablepolyester resins are the condensation products of dicarboxylic acids (ortheir corresponding anhydrides) and dihydric alcohols, polymerizableunsaturation being introduced into the chain by the use of a proportionof α,β-ethylenically unsaturated acid. The polyester resins from whichselection is made are condensation products of polybasic acids (or theircorresponding anhydrides) and dihydric alcohols. Polymerizableunsaturation is introduced into the molecule by the selection of aα,β-ethylenically unsaturated acid, optionally in combination with asaturated acid or anhydride.

Thus suitable acids are, for example, unsaturated aliphatic acids, e.g.maleic, fumaric and itaconic acids; saturated aliphatic acids, e.g.malonic, succinic, glutaric, adipic, pimelic, and azelaic.

Suitable dihydric alcohols are chosen from, for example, ethyleneglycol, poly(ethylene glycols) e.g. diethylene glycol, hexane 1,6-diol,propylene glycol, di-cyclohexanol and neopentyl glycol. Alternatively,the alcohol may be one which initially contained three or more hydroxylgroups, the groups in excess of two optionally being at least in partetherified with, for example, a monohydric alcohol e.g. methanol,ethanol and n-butanol or esterified with monobasic acid, e.g. benzoicacid, p-tertiary-butyl benzoic acid and chain like aliphatic acids of upto 18 carbon atom chain length e.g. coconut oil monoglyceride.

The methods by which unsaturated polyesters of this type are formulatedand made are well known in the art. The resins prefered for thisinvention are formulated with a glycol excess. The glycol excessdetermines the final viscosity.

It is preferred in the working of the present invention that the acidvalue of the polyester lie within certain limits. We have found itpreferable to select polyesters whose acid values lie in the range 5-50mg KOH/g, preferably 10-25 mg KOH/g and most preferably 15-20 mg KOH/g.Acid values greater than 23 may result in low opacity beads when used incoatings. If the acid values are much less than 15, instability mayoccur during the curing stage. This results in the formation of beadaggregates and in the extreme case, complete aggregation of the batchcan occur.

The unsaturated monomer in which the unsaturated polyester resin isdissolved and cross-linked must be essentially water-insoluble. Monomerswhich have a solubility at 20° C. of less than 5% (w/w) in water areconsidered to be suitably water-insoluble for the present purpose. Asingle monomer or a mixture of monomers may be used and in general themonomer will contain only a single polymerizable double bond. However,it is known that polyfunctional monomers, that is, monomers containingmore than one polymerizable double bond, may also be used to cross-linkunsaturated polyester resins. Such polyfunctional monomers are, however,normally present only as a minor constituent of a mixture of monomers,the major proportion of which is monofunctional monomer. Hence mixturescomprising e.g. divinyl benzene may be used in the performance of thepresent invention.

The preferred ethylenically unsaturated monomers are selected fromstyrene, the mixed isomers of methyl styrene commercially available as`vinyl toluene` and methyl methacrylate, because of the ease with whichthay can be copolymerised with the unsaturated resin. For best results,it is preferred that the monomer comprises at least 50% by weight ofstyrene.

The choice of monomers is not, however, restricted to the above monomersalone. Bearing in mind the requirements that the total monomer must beessentially insoluble in water and also be a solvent for the unsaturatedpolyester resin, there may be present in a minor proportion otherpolymerizable unsaturated monomers to, for example, modify the physicalproperties of the coreacted resins. Typical co-monomers are, forexample, ethyl acrylate, n-butyl methacrylate, and acrylonitrile.

The alkyl acryloyl derivative which is dispersed within the unsaturatedpolyester resin and unsaturated monomer must be essentially watersoluble, or can be made water soluble through the formation of aquaternized structure or by other methods known in the art. A singleacryloyl derivative or a mixture of acryloyl derivatives may be used andin general the acryloyl root structure will contain only a singlepolymerizable double bond. In some cases the acryloyl root structure maycontain two or more polymerizable double bonds.

Typical examples include MAPTAC (methacrylamidopropyltrimethylammoniumchloride), TMAEMC (2-trimethylammoniumethylmethacrylic chloride), DANA(3-dimethylaminoneopentylacrylate) and BAEMA(2-t-butylaminoethylmethacrylate) ##STR3##

In general, we have found that the upper limit of usefulness of suchacryloyl derivatives is up to 30 weight percent of the ethylenicallyunsaturated polyester, preferably 20 weight percent, and more preferably15 weight percent based on the non-volatile portion of both thepolyester resin and the acryloyl derivatives. Higher concentrations ofthe acryloyl derivative quaternized structure, for example, may give adestabilising effect to the emulsion.

Optionally a few percent by weight of a non-polymerizing organic liquid,e.g. n-butanol or toluene, may be mixed with the monomer to increase thesolubility of the polyester resin therein or may be introduced as anincidental part of the process, e.g. in preparing the polyester.

It is highly preferred that there be included in the dispersions used inthis invention a surfactant chosen from those which are well known inthe art. Typical examples of suitable species are the sulphates ofnonylphenol and dodecylphenol ethoxylates wherein the alkylene oxidechain comprises at least 5 ethylene oxide units. The surfactant L istypically present to the extent from 0.75-7.5% (preferably 3.0-4.5%) byweight of dispersant solids per volume of total granule solids and maybe added initially to any of the phases of the dispersion prior topolymerization.

The base used in this invention may be selected from the polyamine basesof the variety described by Gunning in U.S. Pat. Nos. 3,879,314 and3,923,704 or the metal oxide, hydroxide and salt bases described byBeresford in U.S. Pat. No. 4,321,322. We have found the preferred baseis magnesium oxide. When an amine base is used, sufficient amine shouldbe present such that there are present from 0.3-4.0, preferably 1.3-3.2amine groups per polyester carboxyl group. When a metal oxide, hydroxideor salt base is used, sufficient base should be present such that thereis present from 0.8-1.8 equivalents of metal cation per equivalent ofpolyester carboxyl group.

Particulate solids, as hereinbefore described, may be optionallyincluded in the dispersions according to the present invention.

The particulate fillers may be dispersed in the polyester solution priorto the emulsification of water therein, or into the water to beemulsified therein or into both, the incorporation into the water beingan especially convenient method. The incorporation of the filler orfillers may be carried out using methods and dispersing agents known tothe art. A further method of imparting pigmentation is the addition ofbase in excess of the quantity needed for complete neutralization of thecarboxyl groups of the polyester resin. All of the bases preferred inthe present invention are capable of acting as extender pigments andsome of them, for example, zinc oxide, are primary opacifying pigmentsin their own right. Thus, the addition of a quantity of base in excessof that required for complete neutralization of the carboxyl groups forthe purpose of pigmentation is encompassed by the present invention.

Unusual effects may be produced in a material comprising granules inwhich the filler is at least in part coloured. For example, the fillermay comprise iron oxide, phthalocyanine, quinacridone or the like.Chemical or physical tagging agents may be included in the vesicles orin the dispersion stage, included are dyes, ultra-violet absorbers,quenchers, or brighteners, fluorescent materials and like additives.

Preferably, the particulate solids concentration is no more than 60% byvolume of the vesicle. While the size of the chosen particles depends onthe actual vesicle diameter, it is prefered that the maximum particlediameter should be 10 microns.

The preferred method of preparation of granules is the "double emulsion"method referred to hereinabove. The initial stage in the preparation ofthe novel polymeric vesiculated granules is the emulsification of waterinto the solution in ethylenically unsaturated monomer or carboxylatedunsaturated polyester resin (the solution in ethylenically unsaturatedmonomer of carboxylated unsaturated polyester resin shall hereinafter bereferred to as "the polyester solution" and the emulsion of water in thepolyester solution shall hereinafter be referred to as the "firstemulsion"). The alkyl acryloyl derivative may be added to the polyestersolution or to the water in the first phase with mechanical agitation.The amount of the alkyl acryloyl derivative added to the polyester resinsolution is a portion of the total amount desired such that when theremaining portion is added to the second emulsion stage the stabledouble emulsion of system is maintained. Preferably, the alkyl acryloylderivative should be added in the ratio of from 0:100 to 55:45, firstemulsion:second emulsion on a weight basis. The mechanical agitation iscontinued until the viscosity of the emulsion is essentially constant.

The agitation is carried out in the presence of the base which may bepresent in the polyester solution, the water or both. If pigmentedgranules are required, the pigment may be added at this stage, or it maybe added to the water, the polyester solution or both prior to theformation of the first emulsion.

The first emulsion is dispersed in water which contains the secondportion of the alkyl acryloyl derivative and a stabilizer for thedispersed first emulsion particles and stirred until the desired granulesize is achieved; this is the "double emulsion". The stabilizer may bechosen from the wide range of materials known to be suitable for thispurpose but we have found that an especially suitable material is awater-soluble partially hydrolysed poly(vinyl alcohol) with a degree ofhydrolysis of 86 to 89% and a viscosity of 44-50 centipoise (30° C. 4%wt. solution, BL type viscometer). A concentration of stabiliser of theorder of 0.1-2.0 % by weight of the total water (vesicular water andcontinuous phase water) gives satisfactory results.

The surfactant may be added at any stage of the process prior topolymerization and to any phase of the double emulsion.

Polymerization of the polyester resin is effected by free radical means.This can be achieved by the use of a free radical initiator such as anorganic peroxide or by exposure to a radiation source such asultra-violet radiation or a radioactive element. When a free radicalinitiator is used it may be conveniently dissolved in the polyesterresin solution before the dispersion of the solution in water or it maybe added to the continuous water phase following the formation of thedouble emulsion.

The preferred initiation system is a redox system of diethylene triamineand cumene hydroperoxide triggered by ferrous ions derived from ferroussulphate. These three materials are added in the following sequentialorder to the continuous phase: ferrous sulphate, diethylene triamine,and cumene hydroperoxide.

With the incorporation of the alkyl acryloyl derivatives in the firstand second emulsion stages the vesiculated polyester granules thusformed have excellent colloidal stability and anti-settling properties.The shelf storage life of the emulsion is extended beyond thatreasonably expected for granules prepared without the acryloylderivatives. The aqueous slurry of vesiculated polyester granules thusformed may be used directly in an aqueous paint formulation, or in papercoatings, or paper wet-end applications. The aqueous slurry ofvesiculated polyester granules may be dewatered, by any convenientmeans, for example by the method described in U.S. Pat. No. 4,154,923and subsequently redispersed in an aqueous or non-aqueous medium, orincorporated into a paste, for example, for use as a filler or a putty,or in a polymer film.

The paper compositions prepared using granules as hereinbefore definedhave consistently improved first-pass retention.

The papermaking process can be carried out using a conventional furnishformed in part or totally from hardwood, softwood and recycled pulpsand/or broke if desired incorporating an internal sizing agent, forexample, natural and fortified rosins or an aqueous ketene dimeremulsion.

The aqueous compositions of use in accordance with this invention can beemployed in alkaline papermaking system, that is systems in which thepaper furnish is maintained at a neutral or alkaline pH value, or in anacid papermaking system, that is systems in which the paper furnish ismaintained at an acid pH value.

In yet a further feature the invention provides paper containingdispersed therein vesiculated polymer granules as hereinbefore defined.

The invention is further described with reference by way of example onlyto the following examples in which all parts are expressed by weight.

EXAMPLE 1

This example illustrates the preparation of 10 micron pigmentedvesiculated polyester resin granules in which the alkyl acryloylderivative is in the first and second emulsion stages. In this examplethe alkyl acryloyl derivative was MAPTAC.

    ______________________________________                                        GROUP   MATERIAL             PARTS (W/W)                                      ______________________________________                                        A       water                    3.089                                                dispersant      (1)      0.237                                                antifoam        (2)      0.014                                        B       titanium dioxide pigment                                                                      (3)      9.250                                        C       MAPTAC          (4)      0.237                                        D       water                    4.267                                        E       water                    1.292                                        F       polyester       (5)      7.592                                                styrene         (6)      4.211                                                magnesium oxide (7)      0.042                                        G       hydroxyethyl cellulose                                                                        (8)      7.538                                                poly(vinyl alcohol)                                                                           (9)      4.377                                                MAPTAC                   0.984                                                water                    28.628                                       H       water                    25.701                                       I       ferrous sulphate                                                                              (10)     0.003                                                diethylene triamine                                                                           (11)     0.041                                        J       cumene hydroperoxide                                                                          (12)     0.080                                        K       bactericide     (13)     0.073                                                ammonia solution                                                                              (14)     0.165                                                water                    2.179                                                                         100.000                                      ______________________________________                                         .sup.(1) Dispersant: a 60% wt. solids ammonium nonylphenoxypolyethoxy         sulphate in ethanol. Fenopon* CO436 (ex. GAF Corp)                            .sup.(2) Antifoam: mineral oil and surfactant blend. Proprietary              Foamaster* NSl (ex. Diamond Shamrock)                                         .sup.(3) Titanium dioxide pigment: rutile grade with organic surface          treatment on an alumina based inorganic coating. Tioxide* RHD6X (ex.          Tioxide)                                                                      .sup.(4) MAPTAC: a 50% weight solids solution in water Mhoromer* BM613        (ex. Rohm Tech.)                                                              .sup.(5) Polyester: a 65% wt. solids solution of a 4.216/2.566/1.000          (molar) propylene glycol/maleic anhydride/phthalic anhydride solution in      styrene                                                                       .sup.(6) Styrene: commercially available material (ex. Dow Chemical)          .sup.(7) Magnesium oxide: commercially available light grade (ex. BDH         Chemicals)                                                                    .sup.(8) Hydroxyethyl cellulose: a 1.5% wt. solids aqueous solution of        hydroxyethyl cellulose. Natrosol* 250 HR (ex. Hercules) specification: (i     viscosity = 1500-2500 cp. Brookfield at 25° C. using 1% wt.            solution (ii) molar substitution for ethyl = 2.5                              .sup.(9) Poly(vinyl alcohol): a commercially available 7.5% wt. solids        aqueous solution of poly(vinyl alcohol) BP24 (ex. Chang Chun Petrochemica     Co. Ltd., Taipei, Taiwan) specification: (i) degree of hydrolysis = 86-89     (ii) viscosity = 40-50 centipoise BL type viscometer at 30° C.         using a 4% wt. solution                                                       .sup.(10) Ferrous sulphate: commercially available material (ex. J. T.        Baker Chemical Co.) specification: hepta hydrate                              .sup.(11) Diethylene triamine: commercially available material (ex. Union     Carbide)                                                                      .sup.(12) Cumene hydroperoxide: a commercially available 78% active           material (ex. Pennwalt)                                                       .sup.(13) Bactericide: a commercially available 20% wt. active aqueous        dipropylene glycol solution of 1,2benzisothiazolin-3-one. Proxel* GXL (ex     Imperial Chemical Industries PLC)                                             .sup.(14) Ammonia: a commercially available 30% wt. solution ammonium         hydroxide in water. (ex. Stanchem)                                            *= trade mark                                                            

The pigmented vesiculated polyester resin granules were made as follows:

Materials "A" were mixed and pigment "B" added to "A" at a uniform ratewhile stirring. Stirring was increased to a high speed and continueduntil the pigment was completely dispersed. Material "C" was added whilestirring, the water "D" was added to give a millbase.

Materials "F" were mixed until the magnesium oxide was completelydispersed. The millbase was washed into "F" using water "E". This wasmixed with high speed stirring until the dispersed particles of themillbase were at least one micron in diameter. This is referred to asthe "first emulsion".

Materials "G" were blended together and the temperature adjusted suchthat when the first emulsion was added to materials "G" the resultingtemperature was 25° C. The attention to the final temperature was foundto be critical. The first emulsion was added to the temperature adjustedmaterials "G". The stirring was maintained at high speed until thedroplets of the first emulsion were essentially ten microns or less indiameter. This s referred to as the "second emulsion".

The speed of the mixer was dropped to a slow stir. The "H" stage watertemperature was adjusted such that the resulting temperature, when addedto the double emulsion, would attain 35° C. The "H" stage water wasadded to the double emulsion.

Materials "I" were added to the second emulsion. The ferrous sulphatewas first dissolved into a small amount of, hot water before addition.

Material "J" was added, then the mixer was turned off. This was leftundisturbed for a minimum of three hours to effect curing.

Materials "K" were added after curing using moderate stirring speed.

EXAMPLE 2

This example illustrates the preparation of 10 micron pigmentedvesiculated polyester resin granules in which the alkyl acryloylderivative is in the second emulsion stage only. For the purposes ofthis example the alkyl acryloyl derivative was chosen to be TMAEMC. Thematerials were as described in Example 1 except as noted.

    ______________________________________                                        GROUP   MATERIAL             PARTS (W/W)                                      ______________________________________                                        A       water                    3.089                                                dispersant               0.237                                                antifoam                 0.014                                        B       titanium dioxide pigment 9.250                                        C       water                    4.267                                        D       water                    1.292                                        E       polyester                7.592                                                styrene                  4.211                                                magnesium oxide          0.042                                        F       hydroxyethyl cellulose   7.538                                                poly(vinyl alcohol)      4.377                                                TMAEMC          (15)     0.763                                                water                    28.628                                       G       water                    26.159                                       H       ferrous sulphate         0.003                                                diethylene triamine      0.041                                        I       cumene hydroperoxide     0.080                                        J       bactericide              0.073                                                ammonia solution         0.165                                                water                    2.179                                                                         100.000                                      ______________________________________                                         .sup.(15) TMAEMC: an 80% wt. solids solution in water Mhoromer* BM604 (ex     Rohm Tech.)                                                                   *= Trade Mark                                                            

The pigmented vesiculated polyester granules were made as follows:

Materials "A" were mixed and pigment "B" added to "A" at a uniform ratewhile stirring. Stirring was increased to a high speed and continueduntil the pigment was completely dispersed. The water "C" was added togive a millbase.

Materials "E" were mixed until the magnesium oxide was completelydispersed. The millbase was washed into "E" using water "D". This wasmixed with high speed stirring until the dispersed particles of themillbase were at least one micron in diameter. This is referred to asthe "first emulsion".

Materials "F" were blended together and the temperature adjusted suchthat when the first emulsion was added to materials "F" the resultingtemperature was 25° C. The attention to the final temperature was foundto be critical. The first emulsion was added to the temperature adjustedmaterials "F". The stirring was maintained at high speed until thedroplets of the first emulsion were essentially ten microns or less indiameter. This is referred to as the "second emulsion".

The speed of the mixer was dropped to a slow stir. The "G" stage watertemperature was adjusted such that the resulting temperature, when addedto the double emulsion, would attain 35° C. The "G" stage water wasadded to the double emulsion.

Materials "H" were added to the second emulsion. The ferrous sulphatewas first dissolved into a small amount of hot water before addition.

Material "I" was added, then the mixer was turned off, and the emulsionwas left undisturbed for a minimum of three hours to effect curing.

Materials "J" were added after curing using moderate stirring.

Table A outlines some of the physical parameters obtained when pigmentedvesiculated granules are prepared in accordance with the aforementionedmethods of preparation for 10 micron diameter granules.

                  TABLE A                                                         ______________________________________                                                           10 micron Granules                                         ______________________________________                                        density of dried granules                                                                          0.59 g/ml                                                percent vesiculation.sup.1                                                                         65%                                                      weight solids        21.5%                                                    volume solids        36%                                                      maximum granule size.sup.2                                                                         12 microns                                               median granule size  5.2 microns                                              minimum granule size 3 microns                                                vesicle size.sup.3   0.5-3.0 microns                                          surface pores on granules                                                                          <0.2 micron                                              thickness of granule wall                                                                          0.1-0.5 micron                                           ______________________________________                                         Note:                                                                         .sup.1 vesiculation determined by mercury porisimetry                         .sup.2 granule size determined by Laser Diffraction Granulometer              .sup.3 internal diameters measured using scanning electron microscopy    

EXAMPLE 3

This example illustrates the preparation of 10 micron pigmentedvesiculated polyester resin granules in which the alkyl acryloylderivative is in the first and second emulsion stages. For the purposesof this example the alkyl acrylol derivative was chosen to be MAPTAC.The formulation has been selected as an example for use in paperapplications.

    ______________________________________                                        GROUP     MATERIAL        PARTS (W/W)                                         ______________________________________                                        A         water           3.163                                                         dispersant      0.243                                                         antifoam        0.014                                               B         titanium dioxide pigment                                                                      9.472                                               C         MAPTAC          0.243                                               D         water           4.369                                               E         water           1.323                                               F         polyester       7.774                                                         styrene         4.312                                                         magnesium oxide 0.043                                               G         hydroxyethyl cellulose                                                                        7.719                                                         poly(vinyl alcohol)                                                                           4.482                                                         MAPTAC          1.008                                                         water           29.315                                              H         water           26.318                                              I         ferrous sulphate                                                                              0.003                                                         diethylene triamine                                                                           0.042                                               J         cumene hydroperoxide                                                                          0.082                                               K         bactericide     0.075                                                                         100.000                                             ______________________________________                                    

The materials used and method of preparation follows that for Example 1.

The following series of experiments employ the following terms:

Freeness of pulp is a measure of the drainage rate of water through thepulp and is measured in accordance with the TAPPI (Technical Associationof the Pulp and Paper Industry) Standard T227 om-75 and is also referredto as Canadian Standard Freeness.

Opacity of the paper sheet is expressed as a light scatteringco-efficient (L.S.C.) and measured in accordance, with TAPPI Standard T425 om-81 using light with a wavelength of 572 nanometers.

The term handsheet is used to refer to a paper sheet made in accordancewith and employing the equipment described in the TAPPI standard T205om-81.

Conditioning refers to the conditioning atmospheres of 23° C. plus orminus 1° C., and 50.0+/-2.0 percent relative humidity that the papersheets are exposed to in accordance with TAPPI standard T405 om-83.

Handsheets were prepared by the following general procedure.

The furnish or solids in the pulp slurry comprised 100 percent by weightof a fully bleached chemical hardwood/softwood blend. The pulp was acommercially produced kraft pulp, and was subsequently beaten to aCanadian Standard Freeness of 415 mls. After beating, individual samplesof pulp were disintegrated, stirred, and varied amounts of the pigmentedvesiculated granules added.

The furnish was subsequently passed through a sheetmaker and theresultant handsheet pressed and conditioned.

EXAMPLE 4

The hereinabove general procedure for the preparation of furnishes wascarried out to prepare furnish comprising a fully bleached chemicalhardwood/softwood blend kraft pulp and a filler comprising pigmentedvesiculated polymeric granules (PVG) as described in this invention, orcomprising standard manufacture vesiculated polymeric granules (SPVG).The filer composition was an emulsion form of the pigmented vesiculatedgranules as described in Example 1 for the MAPTAC - PVG granules, orExample 2 for the TMAEMC - PVG granules.

The results are shown in Table B.

                  TABLE B                                                         ______________________________________                                        EXAMPLE 4                                                                                                   %                                                                   %         RETAINED                                        RUN   SAMPLE        ADDED*    OF ADDED L.S.C.                                 ______________________________________                                        1.    Pulp + MAPTAC 22.0      35.1     648                                          - PVG                                                                   2.    Pulp + MAPTAC 27.5      37.5     681                                          - PVG                                                                   3.    Pulp + MAPTAC 33.0      30.1     686                                          - PVG                                                                   4.    Pulp + MAPTAC 38.5      34.0     751                                          - PVG                                                                   5.    Pulp + MAPTAC 44.0      31.5     774                                          - PVG                                                                   6.    Pulp + TMAEMC  3.6      73.3     589                                          - PVG                                                                   7.    Pulp + TMAEMC  6.0      84.8     630                                          - PVG                                                                   8.    Pulp + SPVG   32.3       3.0     497                                    9.    Pulp only     --        --       434                                    ______________________________________                                         *weight solids of granules on weight solids of pulp                      

Example 4, Table B shows that the pigmented vesiculated polyester resingranules in which the alkyl acryloyl derivative is MAPTAC demonstratesgreatly improved retention and higher opacity than the standardmanufacture pigmented vesiculated polyester resin granules. If the runnumber 3 and run number 8 are compared, it can be seen that the granulecomprising the MAPTAC has been retained at a level of 30.1% whereas thestandard granule has been retained at only 3.0%. This improved retentionis reflected in higher opacities. Run number 3, the granule comprisingMAPTAC, has an opacity of 686; whereas run number 8, the standardmanufacture granule, has an opacity of 497.

Example 4, Table B also shows that the pigmented vesiculated polyesterresin granules in which the alkyl acryloyl derivative is TMAEMCdemonstrates greatly improved retention and higher opacity than thestandard manufacture pigmented vesiculated polyester resin granules. Runnumber 6 uses a granule comprising TMAEMC added at a level of 3.6% onpulp (weight solids on weight solids). The opacity obtained for this runis 589. This can be compared to run 8 which uses standard manufacturegranules at an addition level of 32.2%, the opacity obtained is 497.These two runs clearly show that a higher opacity was obtained, usingless weight of granules added, by the use of granules comprising TMAEMC.

We claim:
 1. Paper containing dispersed therein vesiculated granules ofcross-linked carboxylated polyester resin prepared by the free radicalpolymerization of a dispersion comprising (a) an ethylenicallyunsaturated monomer; (b) a carboxylated unsaturated polyester resinhaving an acid value of from 5-50 mg KOH/g; (c) water; and (d) a base;characterized in that said dispersion further comprises an alkylacryloyl derivative of the formula: ##STR4## where R₁, R₂ and R₃ areselected from H and CH₃ ; E is NH or O; R₄ is C₁₋₆ alkyl substitutedwith Z; wherein Z is NR₅ R₆ ; wherein R₅ is C₁₋₄ alkyl and R₆ is H; orR₅ and R₆ are independently C₁₋₃ alkyl; and quaternary C₁₋₃ alkyl saltsof said alkyl acryloyl derivative.
 2. Paper as claimed in claim 1,wherein said alkyl acryloyl derivative is a compound of the generalformula: ##STR5## wherein R₁, R₂ and R₃ are selected from H and CH₃ ; Eis NH or O; and n is 1-3.
 3. Paper as claimed in claim 2, wherein saidvesiculated granules contain up to 65% by weight, expressed as a solidon the solid portion of the granule, of a particulate material.
 4. Paperas claimed in claim 3, wherein said particulate material is a pigment.